Doesn't look like the index really matters. > The team selected the 25 percent of the funds with the best performance over the 12 months through June 2018. The

Doesn't look like the index really matters. > The team selected the 25 percent of the funds with the best performance over the 12 months through June 2018. Then the analysts asked how many of those funds remained in the top quarter for the four succeeding 12-month periods through June 2022. > The answer was none. So it's more that being a top-performing fund in one year doesn't predict you'll be a top-performing fund in the next. 2k is a pretty significant sample size (though it's functionally less since many are tracking the same benchmarks & so should be highly correlated), large enough that we should anticipate dumb luck.